ci: add Windows unit-test job to catch OS-specific path bugs

.github/workflows/test.yaml

@@ -68,3 +68,38 @@ jobs:
 
       - name: Run unit tests
         run: pixi run -e test pytest tests/unit -v
+
+  # Windows unit tests: guard OS-specific behavior (path separators, etc.) that
+  # the Linux jobs above cannot catch — e.g. #1520, where file-protocol paths
+  # rendered with native backslashes broke garbage collection on Windows.
+  # pixi targets linux/osx only (see [tool.pixi] platforms), so this leg uses
+  # pip. Unit tests need no containers, so no Docker/DB is required on Windows.
+  unit-tests-windows:
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        # Exercise both ends of the supported range (requires-python >=3.10,<3.15).
+        python-version: ["3.10", "3.14"]
+    name: unit-tests-windows (py${{ matrix.python-version }})
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0 # hatch-vcs derives the version from git history/tags
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      # NOTE: pip resolves `[project.optional-dependencies].test`, which is a
+      # DIFFERENT set than the pixi Linux legs' `[dependency-groups].test`
+      # (e.g. it omits graphviz). A unit test importing a dep present in only
+      # one set would then pass on Linux but error on Windows (or vice versa) —
+      # a dep-set mismatch that reads like an OS bug. Keep the two `test` sets
+      # in sync when unit-test dependencies change.
+      - name: Install package with test extras
+        run: pip install -e ".[test]"
+
+      - name: Run unit tests
+        run: pytest tests/unit -v